Simultaneous measurement of energy spectrum and fluence of neutrons using a diamond detector

At a Glance

Metadata	Details
Publication Date	2022-07-14
Journal	Scientific Reports
Authors	Jie Liu, Haoyu Jiang, Zengqi Cui, Yiwei Hu, Haofan Bai
Institutions	Peking University, State Key Laboratory of Nuclear Physics and Technology
Citations	12
Analysis	Full AI Review Included

Technical Documentation & Analysis: MPCVD Diamond for Fusion Neutron Diagnostics

This documentation analyzes the research paper “Simultaneous measurement of energy spectrum and fluence of neutrons using a diamond detector” to highlight the critical role of high-quality MPCVD diamond and to position 6CCVD as the premier supplier for advanced fusion and high-energy physics applications.

Executive Summary

This research successfully demonstrates the first simultaneous measurement of neutron energy spectrum and absolute fluence using a Chemical Vapor Deposition (CVD) diamond detector, validating its potential for fusion diagnostics.

Core Achievement: Simultaneous measurement of both energy spectrum and absolute fluence for d-d (5.0-10.5 MeV) and d-t (14.2 MeV) fusion neutrons.
Material Validation: CVD diamond detectors exhibit excellent radiation hardness and high-temperature endurance, making them superior to traditional Si/Ge semiconductors for intense fusion environments (e.g., ITER, EAST).
Methodology: An absolute response matrix (1.0-20.0 MeV) was generated via Monte Carlo simulation, incorporating ten ¹²C and ¹³C nuclear reaction channels, followed by GRAVEL iterative unfolding.
Performance Verification: Measured main-energy neutron fluences showed strong consistency with results obtained from the international standard ²³⁸U fission chamber and EJ-309 liquid scintillator.
Significance: The work confirms the ability of diamond detectors to provide comprehensive neutron diagnostics, crucial for monitoring and controlling scientific fusion devices.
Material Requirement: Success hinges on high-purity, high-quality Single Crystal Diamond (SCD) capable of fast charge collection and high energy resolution.

Technical Specifications

The following hard data points were extracted from the research paper, detailing the experimental parameters and performance metrics of the diamond detector system.

Parameter	Value	Unit	Context
Neutron Energy Range (Measured)	5.0 to 10.5, 14.2	MeV	d-d and d-t fusion neutrons
Response Matrix Simulation Range	1.0 to 20.0	MeV	Absolute response matrix generation
Detector Volume (Nominal)	4.0 x 4.0 x 0.5	mm³	CVD Diamond detector used in experiment
Energy Resolution Correction	4	%	Applied during simulation of deposited energy
Carbon Isotope Abundance (Simulation Basis)	98.93 (¹²C), 1.07 (¹³C)	%	Natural diamond composition
d-t Neutron Fluence (Diamond Detector)	3.75 x 10⁸	n/cm²	Measured at 14.2 MeV
d-t Neutron Fluence (Associated Alpha Particle)	(3.62 ± 0.18) x 10⁸	n/cm²	Standard reference measurement
Deuteron Beam Energy (d-t source)	300	keV	Incident energy on T-Ti target

Key Methodologies

The successful simultaneous measurement relied on a rigorous simulation and deconvolution process, leveraging the unique nuclear properties of carbon.

Absolute Response Matrix Simulation: A self-developed Monte Carlo code (MATLAB) was used to simulate the detector response for neutrons ranging from 1.0 to 20.0 MeV with a 0.1 MeV interval.
Nuclear Reaction Inclusion: Ten critical neutron-induced reactions on carbon were considered (seven for ¹²C and three for ¹³C), including elastic, inelastic, and multi-body reactions (e.g., ¹²C(n, n+3α)).
Nuclear Data Selection: Evaluated nuclear data libraries (ENDF/B-VIII.0, CENDL-3.2, JEFF-3.3) were used to obtain cross sections, angular differential cross sections, and double differential cross sections.
Charged Particle Tracking: Charged particles produced by nuclear reactions were tracked step-by-step (1.0 µm step length, 0.01 MeV energy step) through the diamond volume to calculate total deposited energy.
Pulse Height Spectra Measurement: Experiments were conducted using d-d and d-t neutron sources (Van de Graaff and Cockcroft-Walton generators), with signals recorded by a CIVIDEC diamond detector and CAEN DT5730 digitizer.
Deconvolution and Unfolding: The measured pulse height spectra were deconvoluted using the GRAVEL iterative unfolding method, utilizing the simulated absolute response matrix to simultaneously extract the neutron energy spectrum and absolute fluence.

6CCVD Solutions & Capabilities

The demanding requirements of fusion neutron diagnostics—specifically high radiation tolerance, thermal stability, and precise geometry—are perfectly matched by 6CCVD’s advanced MPCVD diamond capabilities. We offer the materials and customization necessary to replicate and advance this critical research.

Applicable Materials

To achieve the high energy resolution and stability demonstrated in this paper, high-purity Single Crystal Diamond (SCD) is essential.

Application Requirement	6CCVD Material Recommendation	Technical Rationale
High Resolution & Fast Response	Optical Grade Single Crystal Diamond (SCD)	Highest purity SCD ensures minimal defects, maximizing charge carrier mobility and minimizing trapping, crucial for fast timing and high energy resolution.
Extreme Radiation/Temperature	SCD Substrates (up to 10mm thick)	SCD offers superior radiation hardness and thermal conductivity compared to silicon, ensuring detector longevity in intense fusion environments (up to 500 °C).
Large Area Detectors	Polycrystalline Diamond (PCD) Wafers	For applications requiring larger coverage, 6CCVD offers PCD plates up to 125mm in diameter, providing cost-effective large-area coverage while maintaining excellent radiation tolerance.

Customization Potential

The experimental setup utilized a specific detector volume (4.0 x 4.0 x 0.5 mm³). 6CCVD specializes in providing custom geometries and integrated features required for detector fabrication.

Customization Service	Relevance to Neutron Detector Fabrication	6CCVD Capability
Custom Dimensions	Precise sizing for detector arrays and specific beam geometries.	SCD thicknesses from 0.1µm to 500µm; Substrates up to 10mm. Precision laser cutting available.
Surface Finish	Minimizing surface defects to improve charge collection efficiency.	Ultra-high quality polishing: Ra < 1nm (SCD) and Ra < 5nm (Inch-size PCD).
Metalization	Essential for creating ohmic or Schottky contacts (e.g., Au-Si barrier mentioned).	Internal capability for custom metal deposition: Au, Pt, Pd, Ti, W, Cu. Critical for reliable signal readout.
Global Logistics	Ensuring timely delivery of sensitive materials to international research facilities (PKU, CIAE, ITER).	Global shipping options (DDU default, DDP available) to major fusion research centers worldwide.

Engineering Support

6CCVD’s in-house team of PhD material scientists provides authoritative support to ensure optimal material selection for complex nuclear physics projects.

Material Optimization: Our experts assist researchers in selecting the ideal diamond grade (SCD purity, PCD grain size, or BDD doping level) to optimize performance metrics like charge collection distance and energy resolution for specific Fusion Neutron Diagnostics projects.
Response Matrix Validation: We can consult on the material parameters necessary to refine Monte Carlo simulations, addressing the paper’s noted need for improved nuclear reaction data precision at higher neutron energies.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

Tech Support

Original Source

DOI: https://doi.org/10.1038/s41598-022-16235-x